This project is examining the reproductive effects of exposure to certain compounds that are suspected to act on the endocrine system, e.g. they may act like or interfere with hormones such as estrogen. The study is being conducted among Laotian women, as it is suspected that they may have higher exposures to the compounds of interest (pesticides and PCBs) from their homeland and from consumption of fish caught in the San Francisco Bay. Fifty Laotian immigrants were recruited by community workers to collect urine daily during 3 menstrual cycles for measurement of steroid hormones (estrogen and progesterone). Additionally, they provided a blood sample to measure exposure levels, and completed 2 interviews in their native language. These measured levels, as well as the self-reported data on a number of factors including fish consumption, will be examined for possible effects on hormone levels and menstrual function.